diff options
author | Jeff Garzik <jeff@garzik.org> | 2007-02-17 15:11:43 -0500 |
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committer | Jeff Garzik <jeff@garzik.org> | 2007-02-17 15:11:43 -0500 |
commit | f630fe2817601314b2eb7ca5ddc23c7834646731 (patch) | |
tree | 3bfb4939b7bbc3859575ca8b58fa3f929b015941 /kernel/time/clocksource.c | |
parent | 48c871c1f6a7c7044dd76774fb469e65c7e2e4e8 (diff) | |
parent | 8a03d9a498eaf02c8a118752050a5154852c13bf (diff) |
Merge branch 'master' into upstream
Diffstat (limited to 'kernel/time/clocksource.c')
-rw-r--r-- | kernel/time/clocksource.c | 246 |
1 files changed, 184 insertions, 62 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index d9ef176c4e0..193a0793af9 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -29,6 +29,7 @@ #include <linux/init.h> #include <linux/module.h> #include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */ +#include <linux/tick.h> /* XXX - Would like a better way for initializing curr_clocksource */ extern struct clocksource clocksource_jiffies; @@ -48,6 +49,7 @@ extern struct clocksource clocksource_jiffies; */ static struct clocksource *curr_clocksource = &clocksource_jiffies; static struct clocksource *next_clocksource; +static struct clocksource *clocksource_override; static LIST_HEAD(clocksource_list); static DEFINE_SPINLOCK(clocksource_lock); static char override_name[32]; @@ -62,9 +64,123 @@ static int __init clocksource_done_booting(void) finished_booting = 1; return 0; } - late_initcall(clocksource_done_booting); +#ifdef CONFIG_CLOCKSOURCE_WATCHDOG +static LIST_HEAD(watchdog_list); +static struct clocksource *watchdog; +static struct timer_list watchdog_timer; +static DEFINE_SPINLOCK(watchdog_lock); +static cycle_t watchdog_last; +/* + * Interval: 0.5sec Treshold: 0.0625s + */ +#define WATCHDOG_INTERVAL (HZ >> 1) +#define WATCHDOG_TRESHOLD (NSEC_PER_SEC >> 4) + +static void clocksource_ratewd(struct clocksource *cs, int64_t delta) +{ + if (delta > -WATCHDOG_TRESHOLD && delta < WATCHDOG_TRESHOLD) + return; + + printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", + cs->name, delta); + cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); + clocksource_change_rating(cs, 0); + cs->flags &= ~CLOCK_SOURCE_WATCHDOG; + list_del(&cs->wd_list); +} + +static void clocksource_watchdog(unsigned long data) +{ + struct clocksource *cs, *tmp; + cycle_t csnow, wdnow; + int64_t wd_nsec, cs_nsec; + + spin_lock(&watchdog_lock); + + wdnow = watchdog->read(); + wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask); + watchdog_last = wdnow; + + list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { + csnow = cs->read(); + /* Initialized ? */ + if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) { + if ((cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && + (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { + cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; + /* + * We just marked the clocksource as + * highres-capable, notify the rest of the + * system as well so that we transition + * into high-res mode: + */ + tick_clock_notify(); + } + cs->flags |= CLOCK_SOURCE_WATCHDOG; + cs->wd_last = csnow; + } else { + cs_nsec = cyc2ns(cs, (csnow - cs->wd_last) & cs->mask); + cs->wd_last = csnow; + /* Check the delta. Might remove from the list ! */ + clocksource_ratewd(cs, cs_nsec - wd_nsec); + } + } + + if (!list_empty(&watchdog_list)) { + __mod_timer(&watchdog_timer, + watchdog_timer.expires + WATCHDOG_INTERVAL); + } + spin_unlock(&watchdog_lock); +} +static void clocksource_check_watchdog(struct clocksource *cs) +{ + struct clocksource *cse; + unsigned long flags; + + spin_lock_irqsave(&watchdog_lock, flags); + if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { + int started = !list_empty(&watchdog_list); + + list_add(&cs->wd_list, &watchdog_list); + if (!started && watchdog) { + watchdog_last = watchdog->read(); + watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; + add_timer(&watchdog_timer); + } + } else if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) { + cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; + + if (!watchdog || cs->rating > watchdog->rating) { + if (watchdog) + del_timer(&watchdog_timer); + watchdog = cs; + init_timer(&watchdog_timer); + watchdog_timer.function = clocksource_watchdog; + + /* Reset watchdog cycles */ + list_for_each_entry(cse, &watchdog_list, wd_list) + cse->flags &= ~CLOCK_SOURCE_WATCHDOG; + /* Start if list is not empty */ + if (!list_empty(&watchdog_list)) { + watchdog_last = watchdog->read(); + watchdog_timer.expires = + jiffies + WATCHDOG_INTERVAL; + add_timer(&watchdog_timer); + } + } + } + spin_unlock_irqrestore(&watchdog_lock, flags); +} +#else +static void clocksource_check_watchdog(struct clocksource *cs) +{ + if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) + cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; +} +#endif + /** * clocksource_get_next - Returns the selected clocksource * @@ -84,60 +200,54 @@ struct clocksource *clocksource_get_next(void) } /** - * select_clocksource - Finds the best registered clocksource. + * select_clocksource - Selects the best registered clocksource. * * Private function. Must hold clocksource_lock when called. * - * Looks through the list of registered clocksources, returning - * the one with the highest rating value. If there is a clocksource - * name that matches the override string, it returns that clocksource. + * Select the clocksource with the best rating, or the clocksource, + * which is selected by userspace override. */ static struct clocksource *select_clocksource(void) { - struct clocksource *best = NULL; - struct list_head *tmp; + struct clocksource *next; - list_for_each(tmp, &clocksource_list) { - struct clocksource *src; + if (list_empty(&clocksource_list)) + return NULL; - src = list_entry(tmp, struct clocksource, list); - if (!best) - best = src; - - /* check for override: */ - if (strlen(src->name) == strlen(override_name) && - !strcmp(src->name, override_name)) { - best = src; - break; - } - /* pick the highest rating: */ - if (src->rating > best->rating) - best = src; - } + if (clocksource_override) + next = clocksource_override; + else + next = list_entry(clocksource_list.next, struct clocksource, + list); + + if (next == curr_clocksource) + return NULL; - return best; + return next; } -/** - * is_registered_source - Checks if clocksource is registered - * @c: pointer to a clocksource - * - * Private helper function. Must hold clocksource_lock when called. - * - * Returns one if the clocksource is already registered, zero otherwise. +/* + * Enqueue the clocksource sorted by rating */ -static int is_registered_source(struct clocksource *c) +static int clocksource_enqueue(struct clocksource *c) { - int len = strlen(c->name); - struct list_head *tmp; + struct list_head *tmp, *entry = &clocksource_list; list_for_each(tmp, &clocksource_list) { - struct clocksource *src; - - src = list_entry(tmp, struct clocksource, list); - if (strlen(src->name) == len && !strcmp(src->name, c->name)) - return 1; + struct clocksource *cs; + + cs = list_entry(tmp, struct clocksource, list); + if (cs == c) + return -EBUSY; + /* Keep track of the place, where to insert */ + if (cs->rating >= c->rating) + entry = tmp; } + list_add(&c->list, entry); + + if (strlen(c->name) == strlen(override_name) && + !strcmp(c->name, override_name)) + clocksource_override = c; return 0; } @@ -150,42 +260,35 @@ static int is_registered_source(struct clocksource *c) */ int clocksource_register(struct clocksource *c) { - int ret = 0; unsigned long flags; + int ret; spin_lock_irqsave(&clocksource_lock, flags); - /* check if clocksource is already registered */ - if (is_registered_source(c)) { - printk("register_clocksource: Cannot register %s. " - "Already registered!", c->name); - ret = -EBUSY; - } else { - /* register it */ - list_add(&c->list, &clocksource_list); - /* scan the registered clocksources, and pick the best one */ + ret = clocksource_enqueue(c); + if (!ret) next_clocksource = select_clocksource(); - } spin_unlock_irqrestore(&clocksource_lock, flags); + if (!ret) + clocksource_check_watchdog(c); return ret; } EXPORT_SYMBOL(clocksource_register); /** - * clocksource_reselect - Rescan list for next clocksource + * clocksource_change_rating - Change the rating of a registered clocksource * - * A quick helper function to be used if a clocksource changes its - * rating. Forces the clocksource list to be re-scanned for the best - * clocksource. */ -void clocksource_reselect(void) +void clocksource_change_rating(struct clocksource *cs, int rating) { unsigned long flags; spin_lock_irqsave(&clocksource_lock, flags); + list_del(&cs->list); + cs->rating = rating; + clocksource_enqueue(cs); next_clocksource = select_clocksource(); spin_unlock_irqrestore(&clocksource_lock, flags); } -EXPORT_SYMBOL(clocksource_reselect); #ifdef CONFIG_SYSFS /** @@ -221,7 +324,11 @@ sysfs_show_current_clocksources(struct sys_device *dev, char *buf) static ssize_t sysfs_override_clocksource(struct sys_device *dev, const char *buf, size_t count) { + struct clocksource *ovr = NULL; + struct list_head *tmp; size_t ret = count; + int len; + /* strings from sysfs write are not 0 terminated! */ if (count >= sizeof(override_name)) return -EINVAL; @@ -229,17 +336,32 @@ static ssize_t sysfs_override_clocksource(struct sys_device *dev, /* strip of \n: */ if (buf[count-1] == '\n') count--; - if (count < 1) - return -EINVAL; spin_lock_irq(&clocksource_lock); - /* copy the name given: */ - memcpy(override_name, buf, count); + if (count > 0) + memcpy(override_name, buf, count); override_name[count] = 0; - /* try to select it: */ - next_clocksource = select_clocksource(); + len = strlen(override_name); + if (len) { + ovr = clocksource_override; + /* try to select it: */ + list_for_each(tmp, &clocksource_list) { + struct clocksource *cs; + + cs = list_entry(tmp, struct clocksource, list); + if (strlen(cs->name) == len && + !strcmp(cs->name, override_name)) + ovr = cs; + } + } + + /* Reselect, when the override name has changed */ + if (ovr != clocksource_override) { + clocksource_override = ovr; + next_clocksource = select_clocksource(); + } spin_unlock_irq(&clocksource_lock); |